• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.131-142
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• 1999

The objective of this study is to perform finite element analyses using the anisotropic hardening constitutive model on the basis of the total stress concept. An anisotropic hardening constitutive model had been developed in a companion paper, and was then formulated by implicit stress integration and consistent tangent moduli. A nonlinear finite element analysis program was coded including the algorithm, and as a result, the nonlinear solution was accurately calculated and converged to be asymptotically quadratic. In the analysis of a test embankment it was found that the proposed model could predict the displacement of soils more reasonably than the analysis with von Mises type model. In addition the proposed model could predict accurately the actual behavior through the reanalysis of the problem by a reasonable evaluation of the strength parameter.

• Journal of the Korean Society of Radiology
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• v.10 no.1
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• pp.45-51
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• 2016

The purpose of this study was tried to remove the noise and improve the spatial resolution in the computed tomography (CT) by using anisotropic 2-dimensional (2D) diffusion based filter. We used 4-channel multi-detector CT and american association of physicists in medicine (AAPM) phantom was used for CT performance evaluation to evaluate the image quality. X-ray irradiation conditions for image acquisition was fixed at 120 kVp, 100 mAs and scanned 10 mm axis with ultra-high resolution. The improvement of anisotropic 2D diffusion filtering that we suggested firstly, increase the contrast of the image by using histogram stretching to the original image for 0.4%, and multiplying the individual pixels by 1.2 weight value, and applying the anisotropic diffusion filtering. As a result, we could distinguished five holes until 0.75 mm in the original image but, five holes until 0.40 mm in the image with improved anisotropic diffusion filter. The noise of the original image was 46.0, the noise of the image with improved anisotropic 2D diffusion filter was decreased to 33.5(27.2%). In conclusion improved anisotropic 2D diffusion filter that we proposed could remove the noise of the CT image and improve the spatial resolution.

• The Journal of the Acoustical Society of Korea
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• v.7 no.4
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• pp.86-97
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• 1988

본 논문에서는 비등방성 매질에서의 2차원적 회절현상을 수학적으로 모델링하였다. 비등방성 매질의 2차 포물선 근사법과 프레즈넬 근사법을 적용하기 위하여 전파방향에 따른 표면파 속도의 역수를 포물선으로 가정하였다. 128${\circ}$ Rotated $LiNbO_{3}$ 기판을 사용한 SAW IF Bandpass Filter에서의 회절현상을 모의 설계하여 그 결과를 회절현상이 없는 이상적인 경우와 비교하였다. 또한 전산화 모의 설계 결과와 실제로 제작된 SAW Filter 특성결과를 비교하여 $LiNbO_{3}$ 기판을 사용한 SAW Filter에서도 프레즈넬 근사법이 대체적으로 일치하는 것을 알 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.48-55
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• 2005

In this paper, wrinkling behavior for anisotropic membrane was studied. The analyses were done by using membrane elements and the wrinkling was accounted for by the penalty parameter modified material modeling which was implemented to ABAQUS as a user subroutine. The wrinkle model was applied to corner-loaded square membranes in which the effect of the diameter of steel pin, edge cut-off length and the magnitude of shear moduli on the wrinkling was investigated.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.487-494
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• 1997

비등이 발생하는 경사유로에서 이상유동 구조 파악을 위해 국부적 이상유동 변수의 측정이 이루어졌다. 국부 기포율, 국부 기포빈도, 국부기포속도 그리고 국부 기포크기와 같은 기상 관련 이상유동변수는 이중 전기전도도 탐침으로, 액상속도 분포는 Pilot tuba로 측정하였다. 유로의 경사도가 이상유동 구조에 미치는 영향을 파악하기 위해 실험은 수직, 수직으로부터 30도 경사도 및 60도 경사도에서 유량과 열유속을 변화시켜가며 수행하였으며 유동변수의 측정은 경사진 경우에 측면 방향으로의 대칭성을 고려하여 유로 반 단면내 총 91개 지점에서, 수직인 경우에는 13개 지점에서 이루어졌다. 유동조건은 1.4m/s 이하의 평균 액상 겉보기 속도에 제한되었고 유로내 압력은 대기압이며 유동양식은 미포화 비등에 국한되었다. 측정된 이상유동 변수의 분포를 이용하여 경사유로에 적용할 수 있는 distribution parameter와 drift velocity 같은 dirft flux parameter에 대한 상관식이 개발되었다.

• Journal of the Korean Magnetics Society
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• v.4 no.1
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• pp.48-51
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• 1994

We have studied the room temperature anisotropy in the high $T_{c}$ superconductor $YBa_{2}Cu_{3}O_{7}$ by means of the $^{63}Cu$ nuclear quadrupole resonance (NQR). For the magnetically oriented powder samples, NQR signals were obtained only when the RF magnetic field is applied perpendicular to the direction of the crystalline c-axis. Significant differences in the spin-lattice relaxation times ($T_{1}$) and the lineshapes were observed between the unoriented powder sample and the magnetically oriented sample.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.253-256
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• 2001

본 논문에서는 전처리 과정에서 잡음의 효과적 처리를 위해 기존의 필터 방식들이 가지는 단점인 경계 부분의 블러링 현상을 줄이고 정확한 에지 위치를 보존할 수 있는 비등방성 확산 필터를 사용하여 CT나 MRI 2차원 영상 슬라이스들을 만들어내고 이 슬라이스들을 3차원 데이터 셋으로 구성하여 3차원 공간의 볼륨 데이터로 시각적인 영상정보를 얻는데 있다.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.166-167
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• 2003

아조벤젠 그룹의 trans-cis-trans photo isomerization 특성에 의한 광배향 (photoinduced orientation) 성질을 이용하여 아조벤젠이 함유된 폴리머박막에 표면 부조 격자 (surface relief grating)를 만드는 것은 널리 알려져 있다. 특히 최근 들어, 비선형 물질의 주기적인 배열 구조를 만들기 위해서 surface relief grating을 corona poling 하는 방법들이 연구되어 지고 있다. poling된 surface relief grating은 poling 방향으로의 azo분자의 극질서가 유도되기 때문에, $C_{{\infty}v}$점대칭을 가지는 비등방 회절 격자(anisotropic grating)가 되며 2차 비선형 특성 중의 하나인 선형 전기 광학 효과를 나타낼 수 있다. (중략)

• Journal of Energy Engineering
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• v.15 no.1 s.45
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• pp.35-44
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• 2006

This study experimentally investigates effect of boiling heat transfer when ultrasonic vibration was applied. Under the wall temperature condition, temperature distribution in a cavity was measured during the boiling process and heat transfer coefficient of convection, sub-tooled boiling and saturated boiling states were measured with and without ultrasonic vibration, respectively. Also, the profiles of the pressure distribution in acoustic field measured by a hydrophone were compared with the augmentation ratios of heat transfer calculated by local heat transfer coefficient. Result of this study, heat transfer coefficient and augmentation ratio of heat transfer is higher with ultrasonic waves than without one. Especially, augmentation ratio of heat transfer is more increased the convection state than sub-cooled boiling and saturated boiling states. Acoustic pressure is relatively higher near ultrasonic transducer than other points where is no installed it and affects the augmentation ratio of heat transfer.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.162-171
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• 1993

This paper deals with the anisotropy of the mushy region during solidification process of a binary mixture. A theoretical model which specifies a permeability tensor in terms of pricipal values is proposed. Also, the governing equations are modified into convenient forms for the numerical analysis with the existing algorithm. Some test computations are performed for soeidification of aqueous ammonium chloride solution contained in a square cavity. Results show that not only the present model is capable of resolving fundamental characteristics of the tranport phenomena, but also the anisotropy significantly affects the interdendritic flow structure, i.e., double-diffusive convection and macrosegregation patterns.